This invention relates to a device for cleaning an endoscopic observation window which is provided at a distal end of an elongated insertion instrument of a medical endoscope, and more particularly to an endoscopic observation window cleaning device which is particularly suitable for application to a medical endoscope having a narrow insertion instrument of a reduced diameter for insertion into a body cavity.
Generally, endoscopes which are in use in medical fields are largely composed of a manipulating head assembly to be gripped and manipulated by an operator, an elongated insertion instrument extended out on the front side of the manipulating head assembly for insertion into a body cavity, and a universal cable led out from the manipulating head assembly for connecting same to a light source (or to a light source and a processor).
The insertion instrument is provided with at least an illumination window and an observation window on a distal end face. It is usually the case that the illumination window is provided either at one or two positions on the distal end face. A diffuser lens is fitted in each illumination window in front of a light emitting end of a light guide which is connected to a light source. On the other hand, an optical objective lens system is fitted in the observation window, and a solid-state image sensor device is located at the focus of the objective lens system. Further, an outlet of a biopsy channel is opened in the distal end face of the insertion instrument. Therefore, when a diseased portion is spotted as a result of an endoscopic examination, forceps or other biopsy or surgical instruments are passed through the biopsy channel and projected into the body cavity to make a necessary treatment. Further, the endoscope is provided with the so-called observation window cleaning device thereby to spurt a cleaning fluid toward the observation window in case it is contaminated with body fluids or the like. Normally, the observation window cleaning device is provided on the distal end face of the insertion instrument, and largely composed of a jet nozzle for spurting a cleaning fluid, a mixture of a cleaning liquid and compressed air, toward the observation window, and a cleaning fluid supply passage which supplies the cleaning fluid to the jet nozzle. The cleaning fluid supply passage is extended through the insertion instrument and into the universal cable via the manipulating head assembly.
A rigid tip end section which is attached to the fore distal end of the insertion instrument is largely constituted by a rigid support structure and an insulating cap which is fitted on the distal end of the insertion instrument. From the standpoint of strength and machinability, the rigid support structure is formed of metallic material and encased in the insulating cap in such a way as to preclude its exposure to the outside. The rigid support structure is provided with a predetermined number of axial perforations or bores in which the above-mentioned light guide, optical objective lens system, biopsy channel and jet nozzle are to be fitted.
For the endoscopic insertion instrument which is introduced into a body cavity, it is desirable to be as narrow as possible or as small as possible in outside diameter in order to lessen the pains on the side of patients. Therefore, various component parts to be fitted in the endoscopic insertion instrument should be compact and small in size as long as intended functions of these parts are available, and various attempts have been made in this regard, including layout and positional relations of various component parts within the insertion instrument. As a consequence, the thickness of insertion instruments of recently developed endoscopes has been reduced almost to a limit. Nevertheless, there is a strong demand for further reductions in diameter of endoscopic insertion instruments. In addition, to cope with sophistication of endoscopic examinations and treatments or to cope with increases in functions which are required of an endoscope, there has been a tendency toward incorporating an increased number of component parts into an endoscopic insertion instrument, for example, in order to provide two biopsy channels on one endoscopic insertion instrument or to add a lens drive mechanism to an optical objective lens system in an observation window for a zooming function. Accordingly, it is important to position an increased number of required component parts rationally within a limited space of a narrow endoscopic insertion instrument without necessitating to increase its outside diameter.
In view of the foregoing situations, it is an object of the present invention to provide an endoscopic observation window cleaning device which permits to reduce the outside diameter of a narrow endoscopic insertion instrument further to an extremely small size.
It is a more particular object of the present invention to provide an endoscopic observation window cleaning device having a cleaner nozzle fitted in position at a distal end of a narrow endoscopic insertion instrument in such a way as to permit reduction of the outside diameter of the insertion instrument further to an extremely small size.
In order to achieve the above-stated objectives, according to the present invention, there is provided an endoscopic observation window cleaning device for an endoscope having an elongated insertion instrument extended out from a manipulating head assembly, the insertion instrument having an angle section and a rigid tip end section successively connected to a fore end of an elongated flexible body, the rigid tip end section having a rigid casing block connected to a foremost one of angle rings of the angle section by fitting engagement therewith and sheathed in an insulating cap in distal end portions including a distal end face with at least openings for an observation window and an illumination window axially in alignment with corresponding openings in the insulating cap, along with an opening for a cleaner nozzle connected to a cleaning fluid supply passage and arranged to spurt a cleaning fluid toward the observation window, the endoscopic observation window cleaning device comprising: a nozzle fitting portion being axially bored through the rigid casing block of the rigid tip end section and having a small diameter portion and a radially spread large diameter portion opened in the distal end face of the rigid casing block; a notched void portion being formed in the rigid casing block laterally on the outer side of the large diameter portion of the nozzle fitting portion in such a way as to form an outermost segment of the large diameter portion; and a cleaner nozzle fitted in the large diameter portion of the nozzle fitting portion to form a cleaning fluid supply passage along with a connector pipe fitted in the small diameter portion of the nozzle fitting portion and connected in the angle section to a flexible tube from a cleaning fluid supply source; the cleaner nozzle being fitted in the large diameter portion of the nozzle fitting portion and partly in the notched void portion in the rigid casing block; and the connector pipe being in a staggered shape having an angularly bent intermediate pipe section between straight and parallel front and rear pipe sections and the flexible tube being fitted on the rear pipe section of the connector pipe in the angle section at a position offset radially inward relative to the front pipe section and free of interference with other component parts threaded through the angle section.
The foremost one of angle rings which constitute the angle section of the insertion instrument is connected to the rigid casing block of the rigid tip end section. Other angle rings of the angle section are successively and pivotally connected to the foremost angle ring, and various component parts are threaded or fitted internally of the angle section. Therefore, there is little space in the angle section for the connector pipe of the cleaning fluid supply passage to be extended and to be connected to the flexible tube which constitutes a rear part of the cleaning fluid supply passage. Therefore, it is necessary and important to control the position of the connector pipe in the angle section accurately by way of the angularly bent pipe section because otherwise there will arise the problem of interference with other component parts in the angle section. For this purpose, an index mark is provided on a rear end face of the rigid casing block to indicate a direction in which the angularly bent intermediate section of the connector pipe is to be set. Further, a fore end portion of the connector pipe is fitted in the cleaner nozzle which is partly fitted in the notched void portion in the rigid casing block. The notched void portion is provided in the rigid casing block in such a way as to form an outer segment of a nozzle fitting portion, that is to say, to make an extra space for fitting the cleaner nozzle at the distal end of the endoscopic insertion instrument. Seal material is applied on and around outer periphery of the cleaner nozzle in the notched void portion to anchor same in position and to insure air tightness of the insertion instrument.